Construction And Growth Inhibition Of Cisplatin-resistant Ovarian Cancer Of GnRH Receptor Targeting Mesoporous Silica Nanocomposite

Ovarian cancer is a common malignant tumor in female reproductive system with the highest mortality rate among gynecological malignant tumors.It has become the severe threat for the women around the world both in the life and health.Ovarian cancer is almost differentiated from epithelial cell,and malignant germ cell is the second main source.Currently,surgery combined chemotherapy is the main treatment for ovarian cancer.However,the most commonly utilized platinum drugs for chemotherapy have obvious side-effects and increasing drug resistance.Therefore,reducing the systemic toxicity of platinum-based drugs and solving the drug resistance is one of the key directions of current ovarian cancer treatment.Based on magnetic mesoporous silica nanomaterial and GnRH-a which is a gonadotropin releasing hormone analogue with high expression of ovarian cancer surface receptor,a safe and effective Pt（IV）prodrug targeted mesoporous silica nanomaterial are fabricated to solve the problems in this study.The composites have dual targeting effects of magnetic targeting and GnRH receptor targeting,which guarantee the precise targeting to ovarian cancer cells and control drug release.Meanwhile,the composites encapsulate Pt（IV）prodrug,which effectively reduce the systemic toxicity,decrease the side effects of the original drug and prolong the circulation.The main research includes three parts as below:Section 1:fabrication of mesoporous silica nanocomposites with GnRH receptors targeting.1)Synthesis of Fe₃O₄ nanoparticles.2)Surface coating Fe₃O₄ nanoparticles with solid silica layer（nSiO₂）by St?ber method to improve the stability and dispersion characteristics of Fe₃O₄ nanoparticles.3)A layer of mesoporous silica（mSiO₂）was coated on the solid silicon,and core-shell magnetic mesoporous silica nanoparticles（MMSN）were successfully prepared.4)Synthesis of Pt（IV）prodrug.and 5)MMSN loading Pt（IV）cisplatin prodrug through amide bond connection.6)Synthesis of GnRH-a analogue triptorelin based on Fmoc solid phase polypeptide chemical synthesis.7)Preparation of GnRH receptor targeted mesoporous silicon nanocomposite Pt（IV）@MMSN@GnRH-a with covalent cross-linking method on the surface of silicon spheres.The drug loading efficiency of Pt（IV）was 17%in the targeted drug-loaded nanocomposites by ICP-MS,and the drug release rate reached about 41.4%at 72 h.The results demonstrated the drug-loaded nanocomposites had a well super paramagnetic and magnetic targeting.Section 2:Inhibitory effect of GnRH receptor targeting mesoporous silicon nanocomposites on ovarian cancer cells and the reversal of cisplatin resistance.We used ovarian cancer parent cell A2780 and cisplatin resistant cell A2780/CDDP to investigate the inhibitory effect of targeted drug-loaded nanocomposite on the growth of ovarian cancer cells at the cell level.The results of CCK-8 assay and Flow Cytometry assay showed that the drug-loaded nanocomposite had significant inhibitory effect on proliferation and apoptosis of ovarian cancer drug-resistant cells in a concentration-dependent manner.The results of laser confocal fluorescence microscopy and flow cytometry showed that the destination drug-loading nanocomposites had strong magnetic targeting and GnRH receptor targeting,as well as good cellular uptake capability.Section 3:Anti-tumor effect of GnRH receptor-targeted mesoporous silicon nanocomposites in vivo.We successfully established the A2780/CDDP tumor transplantation model of BLAB/c nude mice,and evaluated the inhibitory effect of drug-loaded nanocomposites on tumor growth in vivo by the changes in tumor volume,tumor weight,body weight and survival cycle of nude mice.The results showed that the body weight of the Pt（IV）@MMSN@GnRH-a nanocomposite group was relatively stable.The tumor volume and weight were significantly smaller than that of the normal saline group,the cisplatin prodrug group and the cisplatin active drug group.And the survival time of the nude mice was significantlyprolonged.PrussianbluestainingandHEstainingshowedthat Pt（IV）@MMSN@GnRH-a nanocomposite has well magnetic targeting and no obvious toxic and side effects.In conclusion,this study successfully fabricated a Pt（IV）@MMSN@GnRH-a nanocomposite with GnRH receptor targeting and magnetic targeting to ovarian cancer cells,and performed well in inhibiting the growth of drug resistance ovarian cancer cells.At the animal level,the nanocomposite exhibited a promising anti-tumor activity of cisplatin-resistant ovarian cancer cells,and showed the ability to reverse tumor resistance and reduced toxicity and side-effects.This project is expected to provide a new method for the targeting therapy of drug-resistant ovarian cancer,which has important significances in scientific research and potential clinical prospects.